Update to c/image main branch

> go get github.com/containers/image/v5@main
> make vendor

... to make sure that we don't regress against Skopeo 1.9.3.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

vendor/google.golang.org/grpc/internal/grpcutil/method.go

@@ -39,6 +39,11 @@ func ParseMethod(methodName string) (service, method string, _ error) {
 	return methodName[:pos], methodName[pos+1:], nil
 }
 
+// baseContentType is the base content-type for gRPC.  This is a valid
+// content-type on it's own, but can also include a content-subtype such as
+// "proto" as a suffix after "+" or ";".  See
+// https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md#requests
+// for more details.
 const baseContentType = "application/grpc"
 
 // ContentSubtype returns the content-subtype for the given content-type.  The